Insulating inorganic metal oxide materials, such as ferroelectric materials or perovskite materials, have high dielectric constants and low current leakage which make them attractive as cell dielectric materials for high density DRAMs. Perovskite material and other ferroelectric materials exhibit a number of unique and interesting properties--both physical and electrical. The defining property of a ferroelectric material is that it possesses a spontaneous polarization that can be reversed by an applied electric field. Specifically, these materials have a characteristic temperature, commonly referred to as the transition temperature, at which the material makes a structural phase change from a polar phase (ferroelectric) to a non-polar phase, typically called the paraelectric phase.
Despite the advantages of the high dielectric constants and low leakage, insulating inorganic metal oxide materials suffer from many drawbacks. One major hurdle to incorporating perovskites into semiconductor processing methods is the fact that no reliable method for removing such materials exists. A major problem is that most of the inorganic compounds formed, such as by way of example by dry chemical etching, are solids having high boiling temperatures. In otherwords, conventional dry etching of perovskite materials results in formation of solid compounds, as opposed to gaseous compounds, as in dry etching techniques for other materials which are then easily expelled from the wafer. For example, dry etching of perovskite materials containing barium or strontium typically produces chlorides, such as BaCl.sub.x, SrCl.sub.x, and TiCl.sub.4. Only the latter of these is volatile under typical semiconductor dry etching wafer processing conditions.
Accordingly, there remain needs for development of semiconductor wafer processing methods for removing insulating inorganic metal oxide materials from semiconductor wafer substrates.